1. Field of the Invention
The present invention relates to a structure of an ink jet recording head, and in particular, it relates to heat dissipation of a substrate in which an energy generating portion for discharging an ink is arranged.
2. Related Background Art
In front of recording means (ink jet recording head) of an ink jet recording apparatus, there are formed discharge ports (usually plural pieces) having a size of about several tens μm for discharging an ink droplet. Based on a discharge signal processed inside a recording apparatus based on a recording data transferred from a host device, the ink droplet is discharged from the discharge port, and an image (including characters and symbols) is recorded on a recorded material.
For a representative ink jet recording head, there is a system using an electrothermal conversion element. This system provides the electrothermal conversion element in an ink path in the vicinity of the ink discharge port in the recording head, and by utilizing thermal energy generated by applying an electrical pulse to this element according to a recording signal, bubbles are allowed to be generated in the ink, and by the pressure of the bubbles, the ink is discharged from the discharge port.
As a structure of the ink jet recording head, there is disclosed a structure in Japanese Patent Application Laid-Open No. H10-119292, and in that Publication, there is disclosed a structure having an excellent heat dissipation property by insert-molding an aluminum system alloy material into a resin support member. Further, in U.S. Pat. No. 6,007,176, there is disclosed a structure, which has increased the heat dissipation property by mounting a recording element substrate arranged with the electrothermal conversion element on a radiating fin. Moreover, in Japanese Patent Application Laid-Open No. 2000-187273, there is disclosed an invention, in which a fixing reinforcement of a flexible wiring sheet to the substrate is performed by bonding a dummy lead electrode, which does not perform giving and receiving a recording signal, and a substrate side electrode, in a structure where the lead electrode provided in the flexible wiring sheet and the substrate side electrode provided in the substrate arranged with the recording element are bonded.
In the structure of a conventional ink jet recording head, though heat dissipation from the recording element substrate is mainly performed through a rear surface, which is an adhesion surface of the substrate, through a binding material layer, thermal conductivity of the binding agent of the substrate is usually far inferior to that of a metal.
Further, in the structure disclosed in the above described Japanese Patent Application Laid-Open No. 2000-187273, though heat dissipation through the dummy lead electrode is performed, the lead electrode is provided for the purpose of the fixing reinforcement of the flexible wiring sheet to the substrate, and therefore, the amount of heat generation thereof cannot be said to be sufficient.
In the meantime, in recent year, the ink jet recording head has increased its amount of heat dissipation accompanied with its speeding up and high densification, and for increase of this amount of heat generation, the ink jet recording head is expected to further improve the heat dissipation property.